I'm late to the party, but look up SLC's letter to his mother on real
Indians vs Cooper Indians, in Vol 1 of the letters. Love it. His opinion
changes from youth to seniority, but the fact that he grew up not far from
Keokuk (where his family later settled) and it was originally designated a
Half-Breed Tract...

http://en.m.wikipedia.org/wiki/Half-Breed_Tract

It would seem to affect his general outlook more than the greater slave
question.

ABE